Adjustable cannula systems and devices

ABSTRACT

Various adjustable cannula systems are provided. The systems can include an adjustable cannula capable of expansion and/or contraction having an elongate body with a distal end and a proximal end. The adjustable cannula can be coupled to an upper housing and a lower housing such that rotation of the upper housing results in expansion or contraction of the adjustable cannula. The adjustable cannula can also have a proximal end having a lumen larger than a distal end lumen. A plurality of flanges can be formed in the elongate body by a plurality of slits that span a majority of a length of the cannula, including along or proximate to its proximal end and distal end.

The present application claims priority under 35 U.S.C. §119(e) to U.S.Provisional Patent Application Ser. No. 61/244,841, entitled “AdjustableUniversal Cannula Systems and Devices,” filed Sep. 22, 2009. The entiredisclosure of the priority application is hereby expressly incorporatedby reference in its entirety.

BACKGROUND

1. Field

Embodiments of the invention relate to cannulas and trocars and, inparticular, to devices, systems, and methods for adjusting opening sizesof cannulas.

2. Description of the Related Art

Cannulas typically are tubes inserted into a body part for allowinginsertion of fluids, materials, or instruments through the cannula or toallow the drainage or removal of fluids.

The smaller in cross-section that a cannula is, the less trauma iscaused to the tissue surrounding the cannula. Recent developments inophthalmology provide a good example of the benefits of small diametercannulas. It has become increasingly common for vitreoretinal surgery touse cannulas sized small enough to pass instruments of 23 gauge (ga.) orless through the cannula. This then allows the incision from the cannulasite to be small enough to self-seal without having to use sutures. Thisself-sealing of the incision in-turn allows the cannula to be insertedtransconjunctivally, saving time and eliminating the need to incise andretract the conjunctiva before incising the sclera, as required using 20ga. or larger instruments. While the use of smaller sized cannulas hasbeen beneficial, the necessity of using smaller sized instruments hasreduced the efficiency of some aspects of surgery compared to the olderstandard of using 20 ga. instruments. For example, the use of a vitreouscutter with a 23 ga. or smaller outer diameter takes more time to removevitreous compared to a 20 ga. outer diameter cutter. Also, the insertionof viscoelastic material through a 23 ga. or smaller lumen is moredifficult and time consuming compared to using a 20 ga. lumen.Therefore, it would be desirable to have a cannula system that providesthe small incision advantages of a self-sealing incision while stillallowing the use of more efficient larger diameter instruments.

Certain aspects, advantages, and novel features of the invention aredescribed in this disclosure. It should be understood that not allpossible aspects, advantages, and features may be employed or achievedin accordance with any particular embodiment of the invention.

SUMMARY

Systems and methods related to an adjustable cannula are provided. Insome embodiments, an adjustable cannula system for performing eyesurgery is provided. The system comprises a bottom housing for placementon an eye, the bottom housing comprising first and second lumens. Thesystem further comprises an expandable member configured to increase anddecrease from one diameter to another, the expandable member to bereceived in the first and second lumens of the bottom housing. Theexpandable member includes a distal end for insertion into the eye. Atleast two coupling elements are located at a proximal end of theexpandable member. The bottom housing is configured to engage one of thecoupling elements, while the top housing is configured to engage theother of the two coupling elements. The diameter of the expandablemember can be controlled by rotating the top housing relative to thebottom housing.

In some embodiments, a cannula system is provided that includes anexpandable member formed as a coil that increase and decreases from onediameter to another. The cannula system further includes a bottomhousing for coupling to and receiving the expandable member including alumen defining a maximum diameter and a top housing for coupling to theexpandable member and to the bottom housing. Coupling of the top andbottom housings forms a detent mechanism providing and maintaining aplurality of expandable member diameters when the top housing is rotatedrelative to the bottom housing.

In some embodiments, a cannula system is provided comprising anexpandable tube having a first tab and a second tab. A bottom housing iscoupled to the expandable tube via the first tab and a top housing iscoupled to the expandable tube via the second tab, wherein rotation ofthe top housing relative to the bottom housing results in expansion orcontraction of the expandable tube.

In some embodiments, an adjustable cannula is provided comprising anelongate body having a distal end and a proximal end, wherein theproximal end has a lumen larger than a distal end lumen. A plurality offlanges are formed in the elongate body by a plurality of slits spanninga majority of a length of the elongate body. Material is formed betweenthe flanges at the distal end for maintaining an initial minimumdiameter of the distal end lumen.

In some embodiments, an adjustable cannula is provided comprising anelongate body having a distal end and a proximal end, the proximal endhaving a lumen larger than a distal end lumen. A plurality of flanges isformed in the elongate body by a plurality of slits spanning a majorityof a length of the elongate body.

In some embodiments, an adjustable cannula comprises an elongate bodyhaving a distal end and a proximal end, the proximal end having a lumenlarger than a distal end lumen. A plurality of flanges is formed in theelongate body by a plurality of slits spanning a majority of a length ofthe elongate body. Material is formed between the flanges andsubstantially fills the slits. The material defines an initial minimumdiameter of the cannula, wherein the material has an initial smallcross-sectional width upon insertion into tissue and expands to asubsequent larger cross-sectional width at some time after insertioninto the tissue so that a working channel of the cannula is enlarged bythe material expanding and causing the flanges to separate.

In some embodiments, a cannula system anchored in the pars plana of aneyeball is provided comprising an expandable member that increases anddecreases from one gauge to another by electroactive action.

In some embodiments, an adjustable cannula system is provided comprisingan elongate body having a proximal portion and a distal portion, whereinan inner diameter of the proximal portion is greater than an innerdiameter of the distal portion. A plurality of slits extend from theproximal portion to the distal portion, wherein the slits are configuredto accommodate expansion and contraction of the elongate body.

BRIEF DESCRIPTION OF THE DRAWINGS

The features, aspects, and advantages of the inventions are describedwith reference to the drawings of various embodiments, which areintended to illustrate and not to limit the inventions. The figures aremerely illustrative and may not represent the actual scale and size ofthe device or systems.

FIG. 1 is a cross-section of an eye including a perspective of a cannulain accordance with the present invention;

FIG. 2 is an exploded perspective of the cannula of FIG. 1;

FIG. 3 is a partially assembled view of another example of a cannula inaccordance with the present invention;

FIG. 4 is a partial exploded view of the cannula of FIG. 2;

FIG. 5 is a partial perspective of the cannula of FIG. 2;

FIG. 6 is a perspective of a portion of the cannula of FIG. 2;

FIG. 7 is a perspective of another portion of the cannula of FIG. 2;

FIG. 8 is a perspective view of yet another example of a cannula inaccordance with the present invention;

FIG. 9 is another perspective of the cannula of FIG. 8;

FIGS. 10A and 10B are exploded perspectives of still yet another exampleof a cannula in accordance with the present invention;

FIG. 11 is an elevation of yet another example of a cannula inaccordance with the present invention;

FIG. 12 is a partial perspective of yet another example of a cannula inaccordance with the present invention;

FIG. 13 is a perspective of yet another example of a cannula inaccordance with the present invention; and

FIG. 14 is a perspective of yet another example of a cannula inaccordance with the present invention.

FIG. 15A is a perspective of yet another example of a cannula with upperhousing in accordance with the present invention.

FIG. 15B illustrates the cannula of FIG. 15A being coupled to an upperhousing.

FIG. 15C illustrates the cannula of FIG. 15B being expanded via use of aprobe.

FIG. 16A is a perspective of yet another example of a cannula withhousing in accordance with the present invention.

FIG. 16B illustrates the cannula of FIG. 16A in an expanded form.

FIG. 17A is a perspective of yet another example of a cannula withhousing in accordance with the present invention.

FIG. 17B illustrates a distal portion of the cannula of FIG. 17A in anexpanded form.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Although several embodiments are disclosed, it will be understood thatthe invention described may extend beyond the specifically disclosedembodiments and includes other uses of the invention and obviousmodifications and equivalents. Embodiments of the invention aredescribed with reference to the accompanying figures, wherein likenumerals refer to like elements throughout. The terminology used in thefollowing description is not to be interpreted in any limited orrestrictive manner. In addition, embodiments of the invention maycomprise multiple novel features with no single feature solelyresponsible for its desirable attributes or essential to practicing theinventions described.

The term “cannula” as used is a broad term, and unless otherwiseindicated, may mean, without limitation, a tube, coil, hose, or the likefor insertion into a body part. The term cannula may also encompassdevices with or without trocars or devices where the cannula itself alsofunctions as a trocar to create in incision. Cannulas can be used todeliver or remove fluids, gases, drugs, materials, oils, tissues,instruments, samples, devices, or the like to and from the body. Thediameter of cannulas can be increased, decreased, expanded, orcollapsed. Such adjustments of the cannulas can be performedmechanically, thermodynamically, or by using electrical current.Cannulas can be constructed of any suitable material. For example,metals such as nitinol, stainless steel, or the like, or the cannulascan be formed of various plastics or polymers such as polyamide,parylene, or polyurethane.

The embodiments disclosed herein relate to an adjustable cannula. Incertain embodiments, the adjustable cannula provides an adjustable portopening enabling surgical procedures in various parts of the body. Insome embodiments, the adjustable cannula can be configured to have asmall initial diameter, thereby allowing the adjustable cannula to beinserted into small incisions in the body. During the surgery, thesurgeon can expand the cross-section or diameter of the adjustablecannula to increase the working channel. In some embodiments, theadjustable cannula can be used in tissue having an elastic, flexible, orresilient characteristic, thus advantageously allowing the diameter ofthe adjustable cannula to expand and permitting the tissue to return tothe approximate size of the initial small incision and self-seal withoutthe need for sutures. By removing the need for sutures, patientdiscomfort is reduced and/or the risk of infection is decreased. In thecase of orthopedic surgeries or other surgeries, a reduced initialsurgical opening can minimize scaring and/or decrease the amount ofhealing time as well as the risk of infection.

In certain embodiments, the adjustable cannula can be used in thetechnology fields of orthopedics, ophthalmology, neurosurgery as well asother technology fields. The adjustable cannula can be universal, suchthat is can be applied to many different technologies. In certainembodiments, the adjustable cannula can have diameter range of 3 mm-9 mmin the orthopedics field. In certain embodiments, the adjustable cannulacan have diameter range of 0.4-1 mm in the ophthalmic field. In certainembodiments, the adjustable cannula can have diameter range of 1 mm-4 mmin the neurosurgery and orthopedic fields.

FIG. 1 shows an adjustable cannula 100, in accordance with the presentinvention, and in use in an eye 101. For example, the adjustable cannula100 can be placed transconjunctivally through the sclera 108, as shown,to provide a port opening for placing, inserting and removing, injectingand aspirating, surgical instruments, fluids, gases, or the like.Adjustable cannula 100 may include a top housing or hub 102, a bottomhousing or hub 104, and an expandable member or tube 106. In FIG. 1 andcertain other embodiments, the expandable member is in the form of acylindrical tube (or other conduit with a lumen there through) having adiameter; however, one skilled in the art will appreciate that theexpandable member 106 can assume other forms, including non-tubular(e.g., square, oval, asymmetrical, conical) forms.

Generally, in eye surgery the surgeon makes an incision in the eye usinga separate knife (not shown) and then inserts a cannula into theincision or inserts a cannula simultaneously with an incising trocar(also not shown) inserted in and extending through the cannula.Depending on the size of the incision, sutures may be required to closeand seal the incision after completing surgery. Incisions 20 ga. orlarger generally require sutures to close and seal the incision. The useof sutures may cause complications, for example, suture irritation,inflammation, post-operative astigmatism, scleral pigment changes, orthe like. Accordingly, some surgeons prefer self-sealing suturelesstechniques, for example, making small incisions and inserting a 23, 24,25 ga., or smaller cannula or port into the eye. Typically, incisions of23, 24, 25 ga., or smaller allow the incision to self-seal orsubstantially self-seal after the operation and therefore does notrequire the use of sutures. However, the use of cannulas or ports havinga size of 23, 24, 25 ga., or smaller can affect the efficiency and/orefficacy of the surgery. For example, it generally takes more effort andtime to inject gas and fluid (for example, silicone oil) through a 23,24, or 25 ga. port compared to a 20 ga. port. Additionally, surgeons arelimited in the types and sizes of instruments that can be used duringsurgery using 23 ga. or smaller instruments compared to the oldertraditional 20 ga. instruments. For example, surgeons cannot insert aslarge of a light instrument through a 23 ga. or smaller port compared toa 20 ga. port, thereby possibly impeding the surgeon's ability toilluminate and visualize the posterior chamber of the eye.

In some embodiments, an adjustable cannula 100 is provided. In someembodiments, the adjustable cannula 100 includes an expandable member106 in the form of a tube that is in part cylindrical with a diameter,while in other embodiments, the expandable member 106 can assume otherforms without a diameter, while still being expandable and contractible.In some embodiments, the adjustable cannula 100, as disclosed, may havea small initial diameter for use as a 23, 24, 25 ga., or smaller port,and, advantageously, the surgeon can expand the diameter of theadjustable cannula 100 to increase the working channel to potentiallyaccommodate a 20 ga. or larger instrument. Accordingly, the adjustablecannula system, as disclosed, allows surgeons to make smaller incisionsin the body without sacrificing the greater efficiency of a largerdiameter size of the working channel. The resilient, elastic nature ofthe tissue allows the tissue to return to approximately its initialsmall self-sealing size after removal of the adjustable cannula 100,despite the cannula 100 having expanded the initial incision toaccommodate a larger working channel. In some embodiments, while theadjustable cannula 100 displaces or stretches some surrounding tissueduring use, after contracting and/or removing the adjustable cannula 100from the patient, tissue can return to approximately near or at theiroriginal position prior to displacement or stretching by the cannula.

In certain embodiments, a surgeon may initially insert an expandabletube 106 sized to accommodate a 23, 25, 27, 28 ga. or smaller port inthe eye. During surgery, the surgeon can increase the diameter of theexpandable tube 106 by attaching top housing 102 to the expandable tube106, seating the top housing 102 in the bottom housing 104, attachingthe expandable tube 106 to the bottom housing 104, and rotating the tophousing 102 relative to the bottom housing 104 causing the expandabletube 106 to a least partially uncoil, creating a larger working channel.In certain embodiments, the diameter of the expandable tube 106 can beincreased to 27, 26, 25, 24, 23, 23, 22, 21, 20, 19, 18 ga. (0.4-1 mm),or larger. In some embodiments, the diameter of the tube 106 can beexpanded from a first position to a second position by between about 1%and 80%, or between about 20% and 40%.

FIG. 2 shows the adjustable cannula 100 of FIG. 1 in explodedperspective. Bottom housing 104 includes a first lumen 110, throughwhich tube 106 passes and in which locking mechanism 112 is rotatablyreceived. Bottom housing 104 also includes a second smaller lumen (shownbelow) through which tube 106 is inserted and a slot (also shown below)for coupling with coupling element 114 of tube 106. While the couplingelement 114 is in the form of a tab or protrusion, the coupling elementis not limited to these particular shapes or forms. The flange or lip116 helps to retain the tube 106 in bottom housing 104. The couplingelement 118 of tube 106 couples with the top housing 102 via slot 120.Like coupling element 114, while coupling element 118 is in the form ofa tab or protrusion, the coupling element is not limited to theseparticular shapes or forms. When fully assembled, a user rotating tophousing 102 in a clockwise direction while holding bottom housing 104stationary or rotating bottom housing in a counter-clockwise directioncauses expandable tube 106 to expand. In other embodiments, thecomponents can be configured such that the top housing 102 can berotated in a counter-clockwise direction to cause expandable tube 106 toexpand. Preferably, locking mechanism 112 has a slight taper that mateswith a taper of lumen 110 so that top housing 102 is snuggly androtatably coupled to bottom housing 104. A snap-fit using detents or thelike (not shown), as known by those skilled in the art, may also be usedto ensure that top housing 102 stays coupled to bottom housing 104 yetallows for rotation. Top housing 102 includes a protrusion (shown below)that matingly seats with notches 122, essentially forming a detentmechanism to hold expandable tube 106 at a desired diameter. Thecoupling of the top and bottom housings 102 and 104 forms a detentmechanism providing and maintaining a plurality of expandable tube 106diameters when the top housing 102 is rotated relative to the bottomhousing 104.

Expandable tube 106 is preferably made at least in part of a thin,resilient material such as nitinol (a memory metal) or other shapememory alloy (e.g., Cu—Al—Ni), stainless steel, or other suitablematerial that can form a sufficiently small diameter coil and yet berobust enough not to collapse against the pressure of stretched tissue.In some embodiments, the tube 106 can be composed of a plastic withmetal (e.g., nitinol) pieces embedded therein. In some embodiments,having the exposed portion of the cannula formed of plasticadvantageously minimizes the risk of harm to surrounding tissue causedduring expansion, as plastic is more deformable relative to metal anddoes not apply the same degree of force in multiple directions as metal.In some embodiments, the materials can be biocompatible, or can beprovided with a protective layer (e.g., of aluminum oxide) to enhancebiocompatibility. In some embodiments, the expandable tube 106 can beformed in part of a material that has an elasticity of between 20×10⁶psi and 2×10⁶ psi that allows the expandable tube 106 to return to anoriginal, non-expanded state with ease. Such elastic materialadvantageously allows the expandable tube 106 to be used multiple timesin different surgical operations, without having concern about long-termdeformation.

In some embodiments involving an adjustable cannula 100 with anexpandable coil, the coil can cooperate with tissue to assist in sealingthe interior of the cannula (e.g., such as when the coil is expanded).To minimize the risk of tissue and other materials from becomingcaptured in the expanded coil, the edges of the coil can be slantedtoward the interior portion of the coil, thereby allowing tissue toslide off the slanted edges and away from the interior portion of thecoil during coil expansion or contraction. In addition, in someembodiments, the coil can be provided with a biocompatible coating thatreduces the friction between coil and the tissue/other materials,thereby reducing the risk of capturing tissue and other materials by thecoil. The surface of the coil can be substantially smooth to allowtissue and other materials to slide off the coil, thereby preventingtissue or materials from being captured by the coil. In an embodiment,the coil is substantially tightly wound to reduce the amount of thespace between layers of the coil, thereby preventing tissue and othermaterials from becoming captured by the coil.

FIG. 3 is a partially exploded perspective of another example of anadjustable cannula 124. Adjustable cannula 124 is essentially the sameas the example shown in FIG. 2, except that bottom housing 126 has morenotches 128 for more selectivity regarding the lumen 103 diameter oftube 106. Additionally, bottom housing 126 has several barbs 132 forgrabbing tissue to facilitate rotation of top housing 102 with respectto bottom housing 126 and thus, adjustment of the lumen diameter 130 ofexpandable tube 106. In some embodiments, the barbs 132 are formed andintegrated with the bottom housing 126, while in other embodiments, thebarbs 132 are removably coupled to the bottom housing 126 such that theycan be removed if desired.

FIG. 4 is a partial exploded perspective of the embodiment of FIG. 2,showing the coupling of expandable tube 106 to the top and bottomhousings 102 and 104. Tab 118 of the expandable tube 106 fits into slot120 of the top housing 102 as shown by arrow 134. Arrow 136 shows tab114 of the expandable tube 106 fitting into slot 138 of the bottomhousing 104. Accordingly, in some embodiments, the bottom housing 104 iscoupled to the expandable tube 106 via a first tab 114, while the tophousing 102 is coupled to the expandable tube via a second tab 118.Rotation of the top housing 102 relative to the bottom housing 104results in expansion or contraction of the expandable tube 106.

The view in FIG. 4 also shows the second smaller lumen 140 of bottomhousing 104. The second lumen 140 receives the expandable tube 106.Advantageously the second lumen 140 may be configured to limit a maximumdiameter size to which the tube 106 can be expanded. By so limiting,second lumen 140 is a safety mechanism preventing the expandable tube106 from expanding too much and damaging or tearing the surroundingtissue. For example, the second lumen 140 can be sized to limit the tube106 from expanding beyond accommodating a 20 ga. instrument and protectthe sclera from tearing or other damage. In other areas of the body, thesecond lumen 140 can be configured to limit the tube 106 from expandingbeyond a maximum design limit (example 4 mm) to prevent surroundingtissue from tearing, or becoming damaged.

In certain embodiments, the expandable tube 106, shown in partialperspective in FIG. 5, is a coiled or a wound-up material. Theexpandable tube 106 can be constructed of metal (for example, nitinol),a plastic, or a polymer, or combination thereof. The thickness of thetube 106 material can be about 0.001 inches (0.0254 mm), and can rangefrom about 0.001 inches (0.0254 mm) to about 0.01 inches (0.254 mm). Insome embodiments, the expandable tube 106 can have a length of between 3mm and 15 mm. The expandable tube 106 comprises a distal end (shown inabove figures) for insertion into the eye, and a proximal end 142 whichpreferably remains external to the eye during use. Flange 116 preventstube 106 from passing through lumen 140, shown in FIG. 4.

FIG. 6 is a perspective view of top housing 102 showing attachmentmechanism 112, slot 120, and lumen 144. Lumen 144 receives instrumentsand materials to be inserted into or removed from the eye andcommunicates with lumen 140 of tube 106. Instruments can include, forexample, biopsy devices, scissors, tissue cutting and/or removaldevices, draining devices, endoilluminators, fluid infusion devices, andthe other surgical instruments. A groove 146 spans the diameter of tophousing 102. In some embodiments, an instrument having a mating end canbe inserted into the groove 146 and can assist in clockwise orcounter-clockwise rotation of the top housing 102.

FIG. 7 is a perspective of bottom housing 104 clearly showing firstlumen 110, second lumen 140, notches 122 and slot 138 for coupling withtab 114. From this angle, the notches 122 are shown as grooves along theperimeter of the cannula. Also from this angle, it is shown that in someembodiments the slot 138 can be curved or angled. This design of theslot 138 advantageously helps to secure a tab member 114 within thebottom housing 104.

Thus as has been described above, an adjustable cannula, in accordancewith the present invention, the user can rotate the top housing 102,which engages tab 118 causing the expandable tube 106 to also rotatewith respect to bottom housing 104. Depending on the direction of therotation, the expandable tube 106 either coils or uncoils causing thelumen 140 diameter of the expandable tube 106 to decrease or increase.The coiling or uncoiling can occur because the tab 118 is held fixed orsubstantially fixed or in position through engagement with the bottomhousing 104. In certain embodiments, bottom housing 104 may be anchoredto tissue or held by the physician to allow the relative rotation of tophousing 102. With the tab 118 rotating while the tab 114 is fixed orsubstantially fixed, the expandable tube 106 is increased or decreasedin diameter, thereby increasing or decreasing the diameter of theworking channel, i.e. lumen 140. In certain embodiments, the expandabletube 106 is configured to uniformly expand and contract or substantiallyuniformly expand and contract at the proximal end and the distal end, asthe user rotates the top housing 102. In other embodiments, theexpansion and contraction of proximal end 142 may be greater than theexpansion and contraction of the distal end of tube 106. The expandabletube 106 may be extracted after reducing the expandable tube 106 to asmaller diameter, preferably as small as possible to minimize trauma tosurrounding tissue during extraction.

In certain embodiments, the locking mechanism 112, shown in FIG. 6, canengage the lower housing element 104 to lock the top housing 102 in auser selected position and maintain a particular diameter of theexpandable tube 106. The locking mechanism 112 can comprise flexiblefingers 148 extending distally and with spacing 150 between each finger148. In certain embodiments, the distal ends of the fingers 148 areconfigured to taper or push outward so as to exert a radial outwardforce against the inner surface of bottom housing 104 defining lumen 110to engage the top housing 102 with the bottom housing 104 and retain thetop housing 102 connected with the bottom housing element 104. Incertain embodiments, lumen 110 is partially conical or tapers. Saidanother way, the lumen 110 has a wider distal end (larger diameter) anda narrower proximal end (smaller diameter). In certain embodiments, thefingers 148 form a partially conical shape, i.e. the fingers 148 form awider distal region (larger diameter) and narrower proximal region(smaller diameter). In certain embodiments, the user may pull the tophousing 102 proximally outward or away from the bottom housing 104causing the flexible fingers 148 to be pushed inward as the flexiblefingers 148 are forced into the narrower portions of the lumen 110. Whenthe top housing 102 is released by the user, the resilient force of theflexible fingers 148 pushes the fingers 148 distally inward into thelumen 110, allowing the flanges to return to a more relaxed state.

FIG. 8 discloses another example of an adjustable cannula 200 wherecannula 200 is an elongate body with a proximal end 202, a distal end204, and a middle region 206 between the proximal and distal ends. Ascan be seen, there is no particular structure delineating the proximalend 202 from the middle region 206 or the middle region 206 from thedistal end 204. The terms proximal end, middle region, and distal endare intended to refer to the general areas of the cannula 200 and not toa specific spot or place on cannula 200. The initial diameter of theadjustable cannula 200 at the proximal end 202 can be larger than theinitial diameter of the cannula 200 at the distal end 204 and the middleregion 206. In certain embodiments, the distal end 204 and the middleregion 206 are formed by elongated flanges 208 configured to flex whenan object, fluid, gas, tissue, device, or the like is inserted throughthe lumen 210. As the flanges 208 flex, the working channel or diameterof cannula 200 increases and decreases. Sufficient force of the flanges208 pressing against the resilient elastic surrounding tissue allows theincrease of the working channel. Conversely, when the compressive forceof the resilient elastic surrounding tissue presses against the flanges208 is greater than the force exerted by the cannula, the workingchannel will decrease, i.e. the diameter of cannula 200 will decrease.In some embodiments, an instrument (e.g., such as a probe) can beprovided within the cannula that retains expansion of the cannula evenagainst pressure from the tissue.

In some embodiments, the flanges 208 of the cannula 200 are separated byslits 212. The slits 212 of the cannula 200 can cooperate withsurrounding tissue to assist in sealing or maintaining closure of theinterior of the cannula 200. Upon expansion of the cannula walls, theslits 212 of the cannula also expand, such that the openings of theslits 212 can increase. While the increase in size of the slits 212 canexpose the interior lumen of the cannula 200, such that material (e.g.,liquid) within the cannula can leak, the slits 212 of the cannula 200can advantageously cooperate with the surrounding tissue to therebymaintain closure of the interior lumen of the cannula. The tissue, whichis generally elastic, can advantageously occupy all or a portion of thespaces in the openings of the slits, thereby providing a blockingfunction by serving as the “walls” of the cannula. Accordingly, liquidin the cannula can be inhibited from leaking out due to the blockingtissue, even when the cannula 200 is expanded.

In the illustrated embodiment, the cannula 200 comprises two or moreslits 212, such as three, four, five, six, seven or eight slits. Inother embodiments, the cannula 200 comprises a single slit such that thecannula is “C-shaped.” The number of slits 212 can affect theperformance of the cannula in transporting fluids and tissue. Forexample, a fewer number of slits can result in the slit openings or thegap size of the slits being larger in size during cannula expansion,which can result in tissue being inadvertently captured in the slitopenings during contraction following expansion such that the slitsremain open.

Generally, an expanded cannula with fewer slits, can increase the gapsize of the slits may increase, thereby increasing the chances ofcapturing or catching tissue or other unwanted material in the slitswhile the cannula is contracting. While increasing the number of slitsmay reduce the gap size of the slits, and thus the risk of capturing orcatching material in the slits during contraction, the strength orrigidity of the cannula walls may decrease, which is important forpreventing collapse of the cannula during insertion. Accordingly, acannula for insertion may benefit from at least two or three slits andfewer than five or six slits. However, in other embodiments, the numberof slit can range from 2-10, or 1-20, or 1-25. One skilled in the artwill realize however that providing a cannula with at least one slit canprovide numerous advantages over conventional cannulas without slits.

The one or more slits 212 advantageously accommodate and modulateexpansion and contraction of the cannula. While the expansion andcontraction can occur by an electrical, mechanical or magnetic means, insome embodiments, the expansion and contraction are performedmechanically means, by insert of, for example, a probe (as shown in FIG.15C). The slits can be positioned symmetrically around the cannula(e.g., three slits at a 120 degrees apart) or asymmetrically. In someembodiments, two or more slits can have similar widths, while in otherembodiments, two or more slits can be of varying widths. In someembodiments, having slits advantageously allow tissue (e.g., scar tissueas in diabetic retinopathy) or other material (e.g., a foreign body suchas a piece of metal during hammering) to be removed from the eye, thathas entered the eye.

In other embodiments, the walls of the slits 212 can be configured toallow tissue or other materials to squeezed out or otherwise removedwhile the walls of the cannula contract from an expanded state. Forexample, the side walls of the slits 212 can be substantially smooth soas to reduce the risk of catching or capturing tissue or other materialsduring contraction. In an embodiment, the side walls of a slit 212 canform a substantially wedge shaped configuration to prevent tissue orother materials from being captured in the slits during contraction. Theopen side of the wedge can face into the interior of the cannula or faceoutwardly to the exterior of the cannula. The side walls of a slit 212can be substantially curved or rounded to prevent tissue or othermaterials from being captured in the slits during contraction. The sidewalls of the slit 212 can also comprise a coating, for example, Teflon,to prevent tissue or other materials from being captured in the slitsduring contraction.

An additional advantage of having a cannula 200 with slits 212 is thatviscous fluids, which would otherwise be very difficult to push througha small cannula, can be more easily pushed through one with the slits212, as the slits 212 can open up under pressure of the fluid. Forexample, infusing 1000 centisoke or 5000 centisoke silicone oil in theeye can result in an opening of the slits when desired. Adding suchfluids removes the need to use an instrument or probe to open the slits212.

In some embodiments, to expand the flanges 208 with slits 212, amechanical means can be provided to force the expansion. In someembodiments, the mechanical means comprises a probe (as shown in FIG.15C) that can be inserted into the cannula 200 to expand the flanges208. The probe can comprise a light source, cutter, diathermy tool, orany other surgical instrument capable of insertion into the cannula 200and forcing expansion of the cannula 200. Other probes can also includebut are not limited to scissors, blades, picks, forceps, and lensremoval devices for dropped lens fragments. In operation, when the probeis inserted into a cannula 200 with slits 212, the interior walls of thecannula 200 will expand outward. In some embodiments, the proximal mostend of the cannula 200 (which may not include a slit) need not beexpandable, and can be set to the maximum probe size available for theprocedure. Advantageously, the slits 212 help to mechanicallyaccommodate and modulate the degree of expansion of the cannula 200.Upon removal of the probe, the cannula 200 will contract to a reducedsize. Accordingly, the adjustable cannula 200 with slits 212 is userfriendly because it requires no forceful mechanical manipulation of thecannula 200 to expand or contract the diameter of the cannula. Further,the adjustable cannula 200 with slits 212 requires no moving parts andthus can be easily manufactured with a single injection molding process.

In some embodiments, one or more probes can be of a single size, suchthat expansion of the cannula 200 is achieved by using multiple probesthat increase in size. For example, in one embodiment, three differentprobes of various increasing gauges (e.g., 25 ga., 23 ga. and 20 ga.)can be used to assist in the expansion of the cannula. In otherembodiments, a probe can be of an adjustable size, such that only asingle probe need be used to assist in the expansion of the cannula 200.

In some embodiments, the probe can have a hollow interior to allow fortools or instruments, as well as liquids and tissue, to passtherethrough. In some embodiments, the probe can therefore serve as bothan expansion tool for the cannula 200 with slits 212, as well as accessport to access a target site.

In certain embodiments, flanges 208 are prevented from separating attheir extreme distal ends by material 214. As the extreme distal ends ofthe adjustable cannula 200 can rest against an eye, preventingseparation of the extreme distal ends of the cannula advantageouslyreduces damages to the eye that can occur during expansion andcontraction of other parts of the cannula. Material 214 may be formed ofthe same material as flanges 208 and molded simultaneously with cannula200 in manufacture, such that the elongate body is a single unitarymolded piece. One skilled in the art will appreciate that material 214is optional, and that in other embodiments, the cannula may beexpandable even at its extreme distal end.

Alternatively, material 214 may be a ring of material placed or attachedto flanges 208, as shown in detail below. Material 214 may serve one ormore purposes. These purposes include maintaining a small initialdiameter of the distal end 204 and middle region 206 as cannula isinserted into tissue by a trocar (not shown) held within cannula 200 andextending beyond distal end 204. Another purpose of material 214 is toallow the flanges to flex and slits 212 to expand under the pressure ofviscoelastic being inserted into the eye, thereby effectively enlargingthe volume of the cannula 200 in the eye to allow faster and easierinjection of viscoelastic. Conversely, when no increased pressure ispresent the flanges 208 may return to an unflexed state with minimalwidth slits 212 to assist in preventing fluid escaping the eye.

An alternate purpose of material 214 is to be only robust enough tomaintain the initial small diameter during insertion of cannula 200 intotissue but weak enough to break upon the insertion of a device larger indiameter than the initial small diameter. In this way, flanges 208 areallowed to separate from each other and flex or bend outwardly toprovide a wider working channel.

Lumen 210 may be large enough to accommodate and define the largestacceptable diameter that flanges 208 are allowed to flex, such as for a20 ga. or greater vitreous cutter, while the distal end and middleregion diameters are small enough to require a minimal sized incision inthe tissue, similar to that describe above with respect to expandabletube 106. In some embodiments, slits 212 can extend a substantiallength, even a majority of the length, of cannula 200 and at least longenough to allow flanges 208 to separate sufficiently to accommodate thelargest diameter device compatible with lumen 210. For example, theslits 212 can extend from a distal end 204 to a wider proximal end 202of the cannula 200. In other embodiments (not shown), instead of aseries of single slits that extend a substantial length of the cannula,a series of multiple slits can extend along a single line and can beprovided to accommodate expansion and contraction of the slits.

As can be seen in FIG. 8, in a non-expanded state, a proximal end 202 ofthe cannula 200 can have a larger diameter than a middle 206 and/ordistal end 204 of the cannula. In some embodiments, the proximal end 202of the cannula 200 remains outside of patient (e.g., outside of an eye)such that it need not be expanded or contracted. Rather, it can be sizedlarger than the middle 206 and/or distal end 204 of the cannula 200 tothereby facilitate the insertion of instruments into the cannula, andprovide greater visual access to a surgeon utilizing the cannula. Forexample, for instruments insertable into the cannula 200 that may have abroader proximal portion (e.g., a handle portion) than a distal portion,the broader proximal portion of the instrument can be inserted with easeinto the broader proximal end 2020 of the cannula 200. After expansionof the cannula 200, the middle 206 and/or distal end 204 can be lessthan, the same as, or greater than the diameter of the proximal end 202of the cannula 200.

In embodiments involving a cannula 200 with slits 212, the cannula 200can be comprised in part or substantially of a plastic material. In someembodiments, to form the cannula, the plastic can be injection molded,such as in a single shot. Different plastic-based materials can be usedto form the cannula 200, including but not limited to organic andsynthetic polymers, polyamide (Nylon), polyoxymethylene (Delrin),parylene, and polyurethane. In some embodiments, the cannula 200 can beformed of a plastic-based material that provides sufficient rigidity tothe cannula 200, while also maintaining some degree of flexible toaccommodate expansion and contraction of the cannula 200 during use. Insome embodiments, the cannula 200 can have a Flexural Modulus of between3×10⁵ PSI and 5×10⁵ PSI. In some embodiments, the cannula 200 can beformed of a plastic with metal pieces embedded therein.

FIG. 9 is a perspective of another example of an adjustable cannula 216in accordance with the present invention. Cannula 216 is essentially thesame as cannula 200 except that material 214 is replaced by ring 218. Insome embodiments, the ring 218 is removable. Ring 218 may be resilientand expandable or rigid, depending on the purpose of using cannula 216.Ring 218 may be adhered to cannula 216 with an acceptable adhesive ormay be held in place by any known attachment mechanism.

The cannulas 200 and 216 may be used alone with a trocar device, or withtop and bottom housings 102 and 104, as shown in FIGS. 10A and 10B. Insome embodiments, the top and/or bottom housings 102 and 104 may be usedto provide more structure to hold cannulas 200 or 216 in place duringsurgery. Though slots 120 and 138 are shown, they are not needed forcannulas 200 and 216. Flange or rim 220 is held between bottom housing104 and the fingers (not shown) of top housing 102.

In FIGS. 10A and 10B, certain features of the top housing 102 and bottomhousing 104 are apparent. The top housing 102 comprises at least oneridge element 107 configured to engage a plurality of grooves or notches122 and 124 in the bottom housing 104. The first and second notches 122and 124 are sized and configured to securely position at least one ridgeelement 107. In certain embodiments, the at least one ridge element 107is configured to fit within notch 122 to lock the top housing 102 into aparticular position. In some embodiments, to rotate the top housing 102to a different position, the user can pull the top housing 102proximally outward and rotate the top housing 102 to disengage the ridgeelement 107 from the notch 122 and engage a second notch 124. Uponrotation of the top housing 102, the cannula 200 can expand or contract.Accordingly, the cannula can be securely kept in a first state while theridge element 107 is in a first notch 122, and securely kept in a secondexpanded or contracted state relative to the first state while the ridgeelement 107 is in a second notch 124.

FIG. 11 shows another cannula 222 and differs from cannula 200 in thatflanges 224 taper so that slits 226 between flanges 224 progressivelywiden towards the distal end of cannula 222, thereby advantageouslyproviding for varied expansion along the length of the cannula. For someapplications, this configuration of flanges 224 may be advantageous suchas providing more space for maneuvering instruments during surgery.

FIG. 12 shows yet another cannula 228 having flanges 230 withthermodynamically changing material 232 filling the space between theflanges 230. Material 230 has an initial small cross-sectional widthupon insertion into tissue and expands to a subsequent largercross-sectional width at some time after insertion into tissue so thatthe working channel of cannula 228 is enlarged by the force of material230 expanding causing flanges 230 to further separate. Material 230 canbe attached between flanges 230 by any known manufacturing techniquesincluding adhesive, molding, injection, etc. Material 230, depending onthe amount of expansion and contraction needed, can be any number ofmaterials such as various hydrogels. Material 230 may begin at a lowtemperature by being quickly treated with a Cryo-device, often used inmany surgeries, immediately before insertion and then material 230 mayincrease in temperature from contact with surrounding tissue andmaterials being injected and aspirated from the surgical site. Asmaterial 230 increases in temperature, material 230 expands. Material230 may also take the form of hydrophilic materials. Hydrophilicmaterials absorb moisture and expand as moisture is absorbed andtherefore material 230 causes flanges 230 to separate from each other,expanding the working channel of cannula 228.

FIG. 13 is yet another example of a cannula 234 having a housing 236with several flanges 238 attached. In this embodiment, housing 236 is asingle molded device having a tapering entry lumen 240 with flanges 238attached by any acceptable method such as adhesive. The entry lumendefines the maximum working channel allowed by cannula 234 and flangesare attached such that they are able to expand and deflect beginningimmediately at the interface with housing 236 at lumen 240. In thisembodiment, the cannula 234 may be formed by insert molding a tube(e.g., nitinol) composed of flanges 238 (e.g. super elastic nitinol)into polymer housing 236. Cannula 234 has several specific features,including several slits (five in this example) distributed substantiallysymmetrically about the cannula body, a wider proximal end than distalend, and the wider proximal end of flanges 238 is within housing 236that is placed on the tissue outside the surgical site.

In certain embodiments, as shown in FIG. 14, an expandable member 306similar to the expandable member 106, is coupled to an electrical energysource 330. The electrical energy source 330 can be configured to applya current to the expandable member 306, which can be controlled by aswitch 319. Depending on the polarity of the current, the expandablemember 306 can be configured to increase or decrease in diameter. Incertain embodiments, the amount of electrical current applied to theexpandable member ranges between 1 nanoamp and 100 microamps. In certainembodiments, the electrical current does not damage or injure the eye orthe surrounding tissue, as the current may be insulated from the tissue(e.g., by an insulating layer). Depending on the current passed throughexpandable member 306, for safety purposes, a grounding path, as isknown, may be used to protect the patient and surrounding tissue fromharm. A ground 327 is operatively connected to the eye 101 to assist inthe grounding process.

In some embodiments, a proximal end of the expandable member 306 iscoupled to the electrical energy source 330. The expandable member 306can be part of a cannula system that can be anchored in the pars planaof an eyeball. The expandable member 306 can increase or decrease fromone gauge to another when electrical energy is applied by the electricalenergy source 330. The expandable member 306 can be extracted byreducing a diameter of the expandable member to a larger gauge byvarying the electrical energy applied by the electrical energy source330.

FIG. 15A is a perspective of yet another example of a cannula with upperhousing in accordance with the present invention. The cannula includesan expandable member 400 including a proximal portion 402 and a distalportion 404. In an unexpanded state, the proximal portion 402 has alarger cross-sectional area than the distal portion 404 to form agenerally conical shape or cone-like configuration. In some embodiments,the expandable member 400 comprises a foldable or winding coil that hasan ending edge 415, as shown in FIG. 15A. In an embodiment, the endingedge 415 is positioned on the surface of the expandable member 400diagonally relative to a longitudinal axis extending between the distalend and proximal end of the expandable member 400 because the diameterof the proximal end is larger than the diameter of the distal end of theexpandable member 400. The ending edge 415 can comprise a substantiallysmooth edge, a curved edge, a slanted edge, a coating, or other edgeconfiguration to prevent tissue from being captured by the ending edge415 as the expandable member 400 expands and contracts. Also shown is anupper housing 482 which can couple with the expandable member 400. Theexpandable member 400 and upper housing 482 form an adjustable cannulasystem that can expand and contract via a mechanical force (e.g., aprobe) as discussed with respect to FIG. 15C.

FIG. 15B illustrates the cannula of FIG. 15A being coupled or beinginserted into an upper housing. The expandable member 400 of the cannulacan be coupled to the upper housing 482 by any of the methods describedabove or can merely placed into the housing be snapped into place or beheld in place due to frictional forces. For example, the expandablemember 400 can include a tab capable of mating with a mateable portion(e.g., a slot) in the upper housing 482. In other embodiments, theexpandable member 400 of the cannula and the upper housing 482 areformed as a single piece.

FIG. 15C illustrates the cannula of FIG. 15B being expanded via use of aprobe. Like the cannula with slits described in above embodiments, thecannula having expandable member 400 in the form of a winding coil canalso be expanded using a probe 450. As the probe is inserted into thecannula, the coiled portion at the distal end and at the intermediateportion begin to unwind to expand the internal working channel of theexpandable member 400. In an embodiment, the proximal end does notexpand because the proximal end of the expandable member 400 comprises alarger diameter than the diameter of the intermediate and distalportion. In some embodiments, the probe 450 is hollow, such thatinstruments, tools or tissue can be introduced through the probe. Insome embodiments, the probe is an instrument or device that can include,for example, biopsy devices, scissors, tissue cutting and/or removaldevices, draining devices, light sources, fluid infusion devices, andthe other surgical instruments. While introducing the probe 450 into theexpandable member 400 can result in expansion, removing the probe 450from the expandable member 400 can result in contraction.Advantageously, like the other cannulas described above, the cannuladescribed in FIGS. 15A-15C allows for introduction into tissue a cannulaof narrow size that can controllably expand only if desired to largersizes, thereby reducing the risk of injury of tissue and the need forsutures. Further, the cannula illustrated in FIGS. 15A-15C does notrequire twisting of the housing portion to expand or contract thediameter of the cannula, rather expansion and contraction occurs when aprobe is inserted or removed from the cannula.

In some embodiments, the cannula 400 is of a material that issufficiently elastic to allow for expansion of one or more coils, andsufficiently stiff to prevent collapse of the cannula during theexpansion. Such material can include various plastics and metals(including metal alloys), as well as plastics with metal embeddedtherein. The geometry of the cannula 400 can also be controlled tominimize the damage to the surrounding tissue performed by the cannula400 when it is introduced and/or expanded within an eye. Controlling thegeometry can provide for sufficient stiffness, while providingsufficient flexibility to the cannula to allow for expansion.

FIG. 16A is a perspective of yet another example of a cannula withhousing in accordance with the present invention. The cannula includesan expandable member 500 including a proximal portion 502 and a distalportion 504, wherein the proximal portion 502 has a largercross-sectional area than the distal portion 504 in an unexpanded state.Along the body of the expandable member 500 are a plurality of flutes orfolds 516. In the illustrated embodiment, the folds 516 extend along amajority of the length of the expandable member 500, from the proximalportion 502 to a furthest most distal end 520 of the distal portion 504,although the folds need not assume such a length in every embodiment(for example, the proximal portion need not be fluted). Due to the folds516, the distal end 520 includes a number of edge points as shown inFIG. 16A. Also shown is a housing 582 which is coupled with theexpandable member 500. The expandable member 500 and housing 582 form anadjustable cannula system that can expand and contract via a mechanicalforce (e.g., a probe) as discussed with respect to FIG. 15C. In someembodiments, the cannula can be formed at least in part of a metal,metal alloy (e.g., nitinol) or polymer, or any combination thereof.

FIG. 16B illustrates the cannula of FIG. 16A in an expanded form thathas been expanded via use of a probe. As the probe is inserted throughthe expandable member 500, the folds 516 of the expandable member 500accommodate expansion. As shown in FIG. 16B, upon expansion, the foldsof the expandable member 500 can expand outward, such that theexpandable member 500 is left with a substantially smooth surface. Also,upon expansion, the expandable member 500 can assume a cylindrical shapesuch that the distal end 520 appears circular. Advantageously, like theother cannulas described above, the cannula described in FIGS. 16A and16B allows for introduction into tissue a cannula of narrow size thatcan controllably expand only if desired to larger sizes, therebyreducing the risk of injury of tissue and the need for sutures.

FIG. 17A is a perspective of yet another example of a cannula withhousing in accordance with the present invention. The cannula includesan expandable member 600 including a proximal portion 602 and a distalportion 604, wherein the proximal portion 602 has a largercross-sectional area than the distal portion 604 in an unexpanded state.Along the body of the expandable member 600 are a plurality of actuatingelements 616 that can expand into a cross-hatched or cage pattern (asshown in FIG. 17B). In the illustrated embodiment, the actuatingelements 616 extend along a majority of the length of the expandablemember 600, from the proximal portion 602 to the distal portion 604,although in other embodiments, the actuating elements 616 can extend alesser portion along the length of the expandable member 600 (e.g., theproximal portion need not have the actuating elements). Also shown is ahousing 682 which is coupled with the expandable member 600. Theexpandable member 600 and housing 682 form an adjustable cannula systemthat can expand and contract via a mechanical force (e.g., a probe) asdiscussed with respect to FIG. 15C. In some embodiments, the cannula canbe formed at least in part of a metal, metal alloy (e.g., nitinol) orpolymer, or any combination thereof.

FIG. 17B illustrates a distal portion of the cannula of FIG. 17A in anexpanded form via use of a probe. As the probe is inserted through theexpandable member 600, the actuating elements 616 of the expandablemember 600 accommodate expansion. As shown in FIG. 17B, upon expansion,the actuating elements 616 can expand outward and form a cross-hatchedor cage pattern. In some embodiments, the cannula in an expanded formcan resemble a wire-frame. In some embodiments, the exposedcross-hatched areas can interact with tissue to provide a seal for thecannula, while in other embodiments, the exposed cross-hatched areas canbe surrounded by a thin film or membrane that can be contractible withthe cannula to prevent liquids and other materials form inadvertentlyentering and/or escaping the lumen of the cannula. Advantageously, likethe other cannulas described above, the cannula described in FIGS. 17Aand 17B allows for introduction into tissue a cannula of narrow sizethat can controllably expand only if desired to larger sizes, therebyreducing the risk of injury of tissue and the need for sutures.

Thus, there has been described several examples of adjustable cannulasthat allow a small initial incision to be made but yet allow use oflarger port sizes during surgery while allowing the incision to returnto a size that may be self-sealing and without the need for sutures. Thefollowing are some comments regarding some possible variations of theexamples described above. These statements and variations are not to beconsidered exhaustive or the only variations possible in accordance withthe present invention, but only for further illustrative purposes.

In some embodiments, the adjustable cannula 200 can be tapered such thatit is of a reduced diameter in a distal portion relative to a proximalportion. In some embodiments, the cannula 200 is configured to benaturally tapered upon entering a body cavity, while in otherembodiments, the cannula 200 is configured to be naturally non-taperedbut will taper in whole or in part upon expansion of the cannula. Insome embodiments, the walls of the cannula 200 are tapered. Theadvantage of having a tapered cannula or tapered walls is thatsurrounding tissue is less likely to be disturbed around the narrowestsections of the tapered cannula 200, and certain tissue will only beaffected if the cannula 200 is expanded.

In some embodiments, the cannula 200 comprises an adjustable seallocated at a distal portion or proximal portion of the cannula, as isknown, to prevent the escape of liquids and gases within the cannula, aswell as the influx of unwanted materials into the cannula 200. As isknown, the seal can comprise a film or diaphragm that adjusts with thecannula during expansion and contraction. In some embodiments, the sealcan comprise a shutter ring or valve that adjusts into various positions(e.g., fully opened, partially opened, fully closed) in accordance withthe state of the cannula. In some embodiments, like the slit openings,the adjustable seal can also interact with surrounding tissue such thatwhen there is an opening in the seal, the surrounding tissue can helpprovide a blocking function.

Conditional language, such as, among others, “can,” “could,” “might,” or“may,” unless specifically stated otherwise, or otherwise understoodwithin the context as used, is generally intended to convey that certainembodiments include, while other embodiments do not include, certainfeatures, elements, or steps. Thus, such conditional language is notgenerally intended to imply that features, elements, or steps are in anyway required for one or more embodiments or that one or more embodimentsnecessarily include logic for deciding, with or without user input orprompting, whether these features, elements, or steps are included orare to be performed in any particular embodiment.

Although this invention has been disclosed in the context of certainpreferred embodiments and examples, it will be understood by thoseskilled in the art that the present invention extends beyond thespecifically disclosed embodiments to other alternative embodiments oruses of the invention and obvious modifications and equivalents thereof.Additionally, the skilled artisan will recognize that any of theabove-described methods can be carried out using any appropriateapparatus. Further, the disclosure herein of any particular feature,aspect, method, property, characteristic, quality, attribute, element,or the like in connection with an embodiment can be used in all otherembodiments set forth herein. Thus, it is intended that the scope of thepresent invention herein disclosed should not be limited by theparticular disclosed embodiments described above.

What is claimed is:
 1. An adjustable cannula system for performing eye surgery, the system comprising: a bottom housing for placement on an eye, the bottom housing comprising first and second lumens; an expandable member configured to increase and decrease from one diameter to another, the expandable member to be received in the first and second lumens of the bottom housing, the expandable member having a distal end for insertion into the eye, the expandable member including at least two coupling elements protruding from only a proximal end of the expandable member, wherein the bottom housing engages one of the coupling elements; and a top housing configured to engage the other of the two coupling elements and control the diameter of the expandable member by rotating the top housing relative to the bottom housing; wherein the at least two coupling elements comprise tabs, wherein a first slot in the bottom housing engages the one of the coupling elements, and wherein a second slot in the top housing is configured to engage the other of the coupling elements.
 2. The cannula system of claim 1, wherein a locking mechanism is configured to maintain the adjustable cannula at a selected diameter size.
 3. The cannula system of claim 1, wherein the top and bottom housings together form a detent mechanism providing and maintaining a plurality of expandable member diameters when the top housing is rotated relative to the bottom housing.
 4. The cannula system of claim 1, wherein the expandable tube comprises memory metal.
 5. An adjustable cannula comprising: an elongate body having a distal end and a proximal end; the proximal end having a lumen larger than a distal end lumen; a plurality of flanges formed in the elongate body by a plurality of slits spanning a majority of a length of the elongate body; material formed between the flanges at the distal end for maintaining an initial minimum diameter of the distal end lumen; a rim formed on the proximal end of the elongate body and configured for placement on an eye; a bottom housing configured to receive the cannula; and a top housing coupled to the bottom housing, wherein the rim is configured to be held between the bottom housing and the top housing.
 6. The cannula of claim 5, wherein the elongate body is a single unitary molded piece.
 7. The cannula of claim 5, wherein the flanges separate under pressure of a material being inserted, allowing the slits to expand and effectively enlarging the volume of the cannula to allow faster and easier injection of the material.
 8. The cannula of claim 5, wherein the material formed between the flanges is robust enough to maintain the initial small diameter during insertion of cannula into tissue but weak enough to break upon the insertion of a device larger in diameter than the initial small diameter, thereby allowing the flanges to separate from each other and flex outwardly to provide a wider working channel.
 9. The cannula system of claim 1, wherein the first lumen extends distal to the second lumen.
 10. The cannula system of claim 1, wherein the bottom housing comprises barbs configured to grab tissue.
 11. The cannula of claim 5, wherein the rim comprises an annular flange.
 12. An adjustable cannula system for performing eye surgery, the system comprising: a bottom housing for placement on an eye, the bottom housing comprising first and second lumens; an expandable member configured to increase and decrease from one diameter to another, the expandable member to be received in the first and second lumens of the bottom housing, the expandable member having a distal end for insertion into the eye, the expandable member including at least two coupling elements protruding from only a proximal end of the expandable member, wherein the bottom housing engages one of the coupling elements; and a top housing configured to engage the other of the two coupling elements and control the diameter of the expandable member by rotating the top housing relative to the bottom housing, wherein the first lumen extends distal to the second lumen.
 13. The cannula system of claim 12, wherein a locking mechanism is configured to maintain the adjustable cannula at a selected diameter size.
 14. The cannula system of claim 12, wherein the top and bottom housings together form a detent mechanism providing and maintaining a plurality of expandable member diameters when the top housing is rotated relative to the bottom housing.
 15. The cannula system of claim 12, wherein the expandable tube comprises memory metal.
 16. The cannula system of claim 12, wherein the bottom housing comprises barbs configured to grab tissue.
 17. An adjustable cannula system for performing eye surgery, the system comprising: a bottom housing for placement on an eye, the bottom housing comprising first and second lumens; an expandable member configured to increase and decrease from one diameter to another, the expandable member to be received in the first and second lumens of the bottom housing, the expandable member having a distal end for insertion into the eye, the expandable member including at least two coupling elements protruding from only a proximal end of the expandable member, wherein the bottom housing engages one of the coupling elements; and a top housing configured to engage the other of the two coupling elements and control the diameter of the expandable member by rotating the top housing relative to the bottom housing, wherein the bottom housing comprises barbs configured to grab tissue.
 18. The cannula system of claim 17, wherein a locking mechanism is configured to maintain the adjustable cannula at a selected diameter size.
 19. The cannula system of claim 17, wherein the top and bottom housings together form a detent mechanism providing and maintaining a plurality of expandable member diameters when the top housing is rotated relative to the bottom housing.
 20. The cannula system of claim 17, wherein the expandable tube comprises memory metal.
 21. An adjustable cannula comprising: an elongate body having a distal end and a proximal end; the proximal end having a lumen larger than a distal end lumen; a plurality of flanges formed in the elongate body by a plurality of slits spanning a majority of a length of the elongate body; material formed between the flanges at the distal end for maintaining an initial minimum diameter of the distal end lumen; and a rim formed on the proximal end of the elongate body and configured for placement on an eye, wherein the rim comprises an annular flange.
 22. The cannula of claim 21, wherein the elongate body is a single unitary molded piece.
 23. The cannula of claim 21, wherein the flanges separate under pressure of a material being inserted, allowing the slits to expand and effectively enlarging the volume of the cannula to allow faster and easier injection of the material.
 24. The cannula of claim 21, wherein the material formed between the flanges is robust enough to maintain the initial small diameter during insertion of cannula into tissue but weak enough to break upon the insertion of a device larger in diameter than the initial small diameter, thereby allowing the flanges to separate from each other and flex outwardly to provide a wider working channel. 